January 14, 2025, 4:15 pm | Read time: 7 minutes

For many people, coffee is part of everyday life, whether it’s for a morning energy boost or a little pick-me-up in between. But did you know that it’s not just the amount you drink but also the timing of your coffee consumption that could play a role in your health? A new study shows that drinking coffee only at a certain time of day could significantly reduce your risk of cardiovascular disease and premature death – regardless of the amount consumed.

Little Is Known About the Health Effects of Coffee at Certain Times of Day

Although there have been numerous studies on the health effects of coffee, little research has been conducted into the influence of the time of day at which coffee is drunk. Coffee, especially caffeinated coffee, has the potential to influence biological processes such as sleep, blood pressure, and inflammation levels. This is due to its influence on the circadian rhythm (the internal circadian rhythm).

The researchers used data from a previous study – the National Health and Nutrition Examination Survey (NHANES) – for their investigations. This determined the health and nutritional status of adults and children in the United States. For validation, the scientists also included participants from two other studies. These were The Women’s and Men’s Lifestyle Validation Study (WLVS and MLVS). The aim was to identify two patterns of coffee consumption – morning versus all day – and assess their association with overall mortality and mortality, specifically from cardiovascular disease and cancer.

Classification of Coffee Consumption into Three Times of Day

For this study, data from adults aged 18 years and older were used from the NHANES^.3 This included information on diet and mortality collected in ten cycles between 1999 and 2000 and 2017 and 2018. The following participants were excluded from the review:

• Individuals who reported cardiovascular disease at baseline.
• People who had been diagnosed with cancer before the start of the study
• People who were pregnant at the start of the study.
• Individuals who had an atypical total energy intake:
  • Women: less than 500 or more than 3500 kilocalories per day
  • Men: less than 800 or more than 4200 kilocalories per day

This resulted in a total of 40,725 adults who were suitable for the present study. In addition, a smaller group of 1463 people – consisting of 772 women and 691 men – from the two sub-studies were included to validate the results.

Assessment of the Time of Day for Coffee

In the NHANES study, participants completed a 24-hour dietary protocol at different intervals. This questioned the time of food intake and the type and quantity of all foods and drinks consumed the day before. This made it possible to track drinking behavior with both caffeinated and decaffeinated coffee. Consumption was divided into three time windows:

• Morning: From four o’clock to 11:59 a.m.
• Afternoon: From twelve o’clock to 4:59 p.m.
• Evening: From 5 p.m. to 3:59 a.m.

The average coffee consumption per day was calculated within these three time periods. This allowed patterns of coffee drinking to be identified using cluster analyses. The sub-studies also asked about the time of food intake as well as the type and quantity. Here, too, the frequency of coffee consumption within the three times of day was determined.

In addition, factors such as the type of coffee (caffeinated or decaffeinated), sleep duration, physical activity, and chronic diseases (e.g., diabetes, high blood pressure) were included in the analysis in order to take potential confounding factors into account.

Estimation of Mortality

By linking the information to the National Death Index, death and mortality data were tracked. The follow-up period was calculated from the start of the first interview to the date of death or the end of the study (December 31, 2019). This resulted in an average follow-up period of 9.8 years.

Coffee in the Morning Increases Longevity

The analysis of the NHANES data showed that 36% of participants were morning coffee drinkers. In contrast, 16 percent consumed the caffeinated beverage throughout the day. The remaining 48 percent were not coffee drinkers. Most of the participants in the sub-studies were also characterized by morning drinking behavior.

The results show that the time of day when coffee is consumed plays an important role. Compared to people who do not drink coffee, morning coffee consumption was associated with a significantly lower risk of all-cause mortality (by 16 percent) and cardiovascular disease mortality (by 31 percent). In contrast, no significant advantage was observed for coffee drinkers who spread their consumption throughout the day.

The amount of coffee consumed also played less of a role for morning coffee drinkers. Whether they drank less than one cup or more than three cups a day – the positive effect on mortality remained. The consumption of coffee in the morning also appeared to be beneficial regardless of whether it was caffeinated or decaffeinated.

The researchers also found evidence that “all-day” coffee consumption may be associated with a higher risk of sleep disturbance and possible circadian rhythm disruption. This could explain the lower health benefits.

Potential Health Benefits of Coffee in the Morning

The study provides new and important insights into how the timing of coffee consumption may affect health outcomes. Coffee in the morning could not only support the circadian rhythm but also positively influence inflammatory processes in the body. Inflammatory markers such as C-reactive protein, which are typically highest in the morning, could be better regulated by the antioxidant properties of coffee.

For the prevention of cardiovascular disease, the results underline the importance of conscious consumption, taking into account not only the quantity but also the time of day. As cardiovascular disease remains the leading cause of death, these findings could help to improve individual and public health strategies.

The results are also relevant in practice. Those who previously drank coffee all day could benefit by switching to morning consumption without having to reduce the total amount.

More on the topic

Study Shows Drinking Coffee or Tea Daily Can Protect Against Some Types of Cancer

Study Shows Sugary Drinks Increase the Risk of 7 Cardiovascular Diseases

Study from Germany Exercise at the Right Time Reduces the Risk of Obesity and Diabetes

Classification of the Study and Possible Limitations

“This is the first study to investigate the timing of coffee drinking and the health consequences,” emphasizes lead author Dr. Lu Qi in a press release^.4 “We don’t usually give advice on the timing of coffee drinking in our dietary advice, but maybe we should think about it in the future.” Furthermore, the study is characterized by a large sample size, a long follow-up period, and the validation of the results in an independent cohort.

Nevertheless, there are some limitations. Firstly, the study is based on observational data, so no causalities can be proven. Secondly, other factors, such as an overall healthier lifestyle among morning coffee drinkers, could have played a role and influenced the results. Thirdly, the data on coffee consumption was collected on the basis of self-reports, which could have led to recall errors. The data mainly originated from the US and may, therefore, not be representative of other population groups.

Furthermore, genetic differences, such as the individual’s ability to metabolize caffeine, were not taken into account in the study. This could influence the results, especially in people with slower caffeine metabolism, who may be more sensitive to afternoon or evening coffee consumption.